﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _5._13作业
{
    class Program
    {
        static void Main(string[] args)
        {
            const double i = 3.14;
            while (true)
            {
                Console.WriteLine("请输入圆的半径");
                int r = int.Parse(Console.ReadLine());
                Console.WriteLine("圆的面积为"+r*r*i);
            }

            //Console.ReadKey();
        }
    }
}
